These conditions can be attributed to the constant flow of the southeasterly winds and increased humidity levels.
Light winds and high humidity levels are two main factors which help pollutants such as smoke and dust particles to entangle with the moisture. Thus, these contaminants remain suspended in the lower atmosphere due to the limited movement of winds resulting in increased levels of pollution.
During winters, such occurrence takes place when a Western Disturbance approaches the hills of North India, and the situation remains the same until the time the system affects the Western Himalayas. As soon as the system moves away, dry and cold winds start blowing from the Northwest direction over the entire Northwestern Plains.
For the last two days, after the passage of the recent Western Disturbance, moderate northwesterly winds have been blowing over Delhi-NCR at a speed of 20-25 kmph. Due to these winds, humidity levels have decreased significantly. Also, the continuous flow of these winds has carried away all the pollutants from the national capital and its adjoining areas.
As per the data by SAFAR, most parts in the national capital recorded sound levels of PM2.5 and were below the 100 mark. For instance, Pusa stood at 68, Lodhi Road 78, Ayanagar 58, Pitampura 70, and Delhi University 73.
For the next 48 hours, pollution levels will remain on the lower side in Delhi-NCR, and Delhiites will get a chance to breathe cleaner air. However, the happiness will be short lived as an east-west trough is expected to develop from Madhya Pradesh to East India leading to a change in the wind direction from northwesterly to easterly or southeasterly.
Thus, once again the wind speed will decrease, and humidity levels will increase furthermore aggravating the pollution levels.
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